Ultrasound imaging system and method for deriving depth and identifying anatomical features associated with user identified point or region

ABSTRACT

An ultrasound imaging system comprises a display for displaying a received ultrasound image. A user interface is provided for receiving user commands for controlling the ultrasound imaging process, and it receives a user input which identifies a point or region of the displayed ultrasound image. An image depth is determined which is associated with the identified point or region and the imaging process is controlled to tailor the imaging to the identified point or region.

RELATED APPLICATIONS

This application is the U.S. National Phase application under 35 U.S.C.§ 371 of International Application No. PCT/EP2018/077259, filed on Oct.8, 2018, which claims the benefit of and priority to EuropeanApplication No. 17196608.8, Oct. 16, 2017. These applications areincorporated by reference herein.

FIELD OF THE INVENTION

This invention relates to medical diagnostic imaging systems and, inparticular, to ultrasound diagnostic imaging systems with user controlof image settings.

BACKGROUND OF THE INVENTION

Ultrasonic diagnostic imaging applications can differ widely in theimaging conditions encountered. When imaging the fetal heart forinstance a high frame rate of display is required to accurately imagethe detail of a rapidly beating heart. In other applications such as thediagnosis of tumors in the liver, a high frame rate is not necessary buta high image quality (resolution) is generally preferred. In some casesthe pathology being diagnosed may be deep within the patient's body. Inother cases the pathology may be just beneath the skin. These widelydiffering conditions mean that the sonographer frequently has to changea wide variety of settings on the ultrasound system in order to acquirethe best images for a given examination.

Typically, the image settings are adjusted on the imaging console beforethe first image is acquired. Once the first image is displayed, theparameters are re-adjusted until the operator is satisfied.

The controls occupy space on either the display unit or on a physicalcontrol unit of the system. Also, the feedback mechanism is indirect,requiring an iterative adjustment process. For example, changing thefrequency from high (resolution, “Res”) to medium (general “Gen”) mayalready have the desired effect on imaging depth, or if not, thefrequency has to be changed again to low (penetration, “Pen”). Asanother example, adjusting the time-gain control changes brightness at acertain image depth, but the user may need to try several controlsliders to adjust the desired depth.

This may make it difficult especially for inexperienced users todirectly find the correct setting, which is why assistance in adjustingsuch parameters is of interest.

WO 2005/059586 for example discloses the automatic determination ofdynamic acquisition parameters. In particular, two of the mostfrequently used user settings, the Resolution/Speed (“res/speed”)control and the Pen/Gen/Res control, are automated. The Res/Speedcontrol adjusts the trade-off between image quality (resolution) andframe rate (speed) by varying imaging parameters such as image linedensity, multiline order, and number of focal zones. The Pen/Gen/Rescontrol adjusts the trade-off between image resolution and the depth ofpenetration of ultrasound through control of imaging parameters such asthe transmit and receive frequencies. In response to a sensed imagemotion and/or noise, the relevant image parameters are automaticallyvaried to obtain images which are a sensible balance of these competingfactors.

This easy adjustment is attractive to a user, but the user may stillwant control over which adjustments are made and how they affect theimage.

There remains a need for simplified user controls but which still giveultimate control to the user for controlling the ultrasonic imaging togive desired tissue penetration, imaging frame rate, and imageresolution.

Document EP 2 702 947 discloses an ultrasound imaging apparatusconfigured with a touch screen display and computer aided measurementand/or diagnosis capability.

Document US 2014/098049 discloses a system for receiving touch-basedinput from an operator of an imaging device.

SUMMARY OF THE INVENTION

The invention is defined by the claims.

According to examples in accordance with an aspect of the invention,there is provided an ultrasound imaging system, comprising:

an ultrasound probe for generating ultrasound signals and receivingreflected echo signals;

a processing system for controlling the generation of the ultrasoundsignals and processing of the received reflected echo signals;

a display for displaying a received ultrasound image; and

a user interface for receiving user commands for controlling thegeneration of the ultrasound signals and/or processing of the receivedreflected echo signals,

wherein the user interface is adapted to receive a user input whichidentifies a point or region of a displayed ultrasound image, and

wherein the processing system is adapted to derive an anatomical featureidentification and/or an image depth associated with the identifiedpoint or region and control the generation of the ultrasound signals andprocessing of the received reflected echo signals to adapt them to theidentified point or region.

This system enables a user to select a point or region of an image, andthe ultrasound imaging parameters may then be controlled automaticallyto optimize the imaging for that particular region. The parameterscontrolled relate to the diagnostic imaging procedure (i.e. theacquisition, processing and display of image data). Examples ofparameters that may be controlled are the focal zone, the frequency, thetime gain compensation settings, overall imaging gain, frame rate etc.These parameters are all for controlling the eventual display such thatit is optimized for the display of a particular anatomical area orfeature of interest, rather than a generic display setting (such as ageneric brightness or contrast setting).

In a simplest implementation, the user identifies the point or region,and a standard parameter optimization is carried out. The depth (fromthe ultrasound head to the region of tissue) of the identified point orregion is for example identified and this enables automated orsemi-automated adjustment of the imaging parameters.

In a system in which depth information is derived, the processing systemfor example may be adapted to adjust the frequency in response to thederived depth. The frequency control is thus used to ensure a minimumamplitude for the echo signal at the particular depth.

The processing system may be adapted to adapt the frequency to maximizethe received signal. This may for example make use of closed loopcontrol.

In a system based on anatomical feature recognition, the processingsystem may be adapted to identify anatomical structures within the imageand to identify an anatomical structure at the identified point orregion, and to control the generation of the ultrasound signals and/orprocessing of the received reflected echo signals to adapt them to theidentified anatomical structure.

The system may then apply the best imaging parameters for a particularanatomical structure. For example, the identification of the mitralvalve, based on a segmentation label, may cause the frame rate to beadjusted. This does not require specific knowledge of the depth for therequired frame rate adjustment to be carried out.

The processing system may be adapted to adjust one or more of:

the frame rate;

the contrast;

the gain settings;

the focal zone.

The frame rate may for example be increased for a moving structure suchas the heart, whereas a lower frame rate for a stationary structure mayenable higher quality imaging. Contrast control may be used to make astructure, such as a ventricle wall, more easily visible.

Model based segmentation may be used to identify the anatomicalstructures, although other approaches, such as machine learning, mayalso be used.

The user interface is for example adapted to receive a further command.This enables the user to have some control over the parameteroptimization as well as or instead of a fully automated option.

In a first example, the further command indicates that focal depthadjustment is desired, and the processing system is adapted to adjustthe frequency and/or scanning aperture in response to the derived depth.The scanning aperture is also used to influence the focal depth.

Thus, in this case, the user may need to specify that depth adjustmentis desired as one of several possible options, instead of a fullyautomated depth adjustment.

In a second example, the further command indicates that focal zoneadjustment is desired, and the processing system is adapted to adjustthe width of the beam at the focus and the focus depth in response tothe derived depth. This beam width is dependent on the frequency andaperture and determines the resolution at the focus and also at otherregions outside the focus.

In a third example, the size of the field of view may be controlled. Byadjusting the field of view, a zoom in operation is implemented to theimage region of interest.

In a fourth example, the further command indicates that a gainadjustment is desired (e.g. overall imaging gain or depth-dependent timegain compensation), and the processing system is adapted to adjust thegain setting, such as the time gain compensation, in response to thederived depth.

Time gain compensation is used to account for tissue attenuation. Byincreasing the received signal intensity with depth, the artifacts inthe uniformity of a B-mode image intensity are reduced. Different timegain compensation functions may be appropriate for different scan lines,and the user can input when time gain compensation changes are desired,but they can then be altered automatically taking into account theidentified point or region.

The user interface may be adapted to receive the further command as oneor more of:

a touch screen pinch command;

a single click mouse or touch screen command;

a double click mouse or touch screen command;

a two finger touch screen interaction;

a mouse or touch screen slider interaction;

a selection from a list of options.

Thus, various touch screen or mouse commands may be used to enable theuser to input commands beyond the mere identification of the point orregion of interest.

The user interface may be adapted to receive the user input whichidentifies a point or region as one or more of:

a touch screen point identification;

a region drawn over a touch screen;

a single click point identification using a mouse;

a region drawn using a mouse.

The initial identification of the point of region of interest may be asimple single click function or a simple region drawing function, againusing a mouse or touch screen.

The invention also provides an ultrasound imaging method, comprising:

generating ultrasound signals and receiving and processing reflectedecho signals;

displaying a received ultrasound image; and

receiving user commands for controlling the generation of the ultrasoundsignals and/or processing of the received reflected echo signals,wherein the user commands identify a point or region of a displayedultrasound image,

wherein the method comprises deriving an anatomical featureidentification and/or an image depth associated with the identifiedpoint or region and controlling the generation of the ultrasound signalsand processing of the received reflected echo signals to adapt them tothe identified point or region.

This method provides automated parameter control based on an identifiedregion of an ultrasound image.

The method for example comprises adapting the frequency in response to aderived depth.

The method may comprise identifying anatomical structures within theimage and identifying an anatomical structure at the identified point orregion, and

controlling the generation of the ultrasound signals and/or processingof the received reflected echo signals to adapt them to the identifiedanatomical structure. Model based segmentation may be used to identifythe anatomical structures.

In response to the anatomical structure identified, the method mayprovide adjustment of one or more of:

the frame rate;

the contrast;

the gain settings;

the focal zone.

Different adjustments may be appropriate for different

The method may comprise receiving a further user command, wherein:

the further command indicates that focal depth adjustment is desired,and the method comprises adapting the frequency in response to thederived depth; or

the further command indicates that focal zone adjustment is desired, andthe method comprises adjusting the width of the beam at the focus andthe focus depth in response to the derived depth; or

the further command indicates that a field of view adjustment isdesired, and the method comprises adjusting the field of view inresponse to the derived depth; or

the further command indicates that time gain compensation adjustment isdesired, and the method comprises adapting the time gain compensation inresponse to the derived depth.

The invention may be implemented at least in part in computer software.

These and other aspects of the invention will be apparent from andelucidated with reference to the embodiment(s) described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Examples of the invention will now be described in detail with referenceto the accompanying drawings, in which:

FIG. 1 shows a first example of an ultrasound system in schematic form;

FIG. 2 shows a second example of an ultrasound system in schematic form;

FIG. 3 shows an ultrasound imaging method; and

FIG. 4 shows in more detail a known component structure of an ultrasoundimaging system.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The invention will be described with reference to the Figures.

It should be understood that the detailed description and specificexamples, while indicating exemplary embodiments of the apparatus,systems and methods, are intended for purposes of illustration only andare not intended to limit the scope of the invention. These and otherfeatures, aspects, and advantages of the apparatus, systems and methodsof the present invention will become better understood from thefollowing description, appended claims, and accompanying drawings. Itshould be understood that the Figures are merely schematic and are notdrawn to scale. It should also be understood that the same referencenumerals are used throughout the Figures to indicate the same or similarparts.

The invention provides an ultrasound imaging system which comprises adisplay for displaying a received ultrasound image. A user interface isprovided for receiving user commands for controlling the ultrasoundimaging process, and it receives a user input which identifies a pointor region of the displayed ultrasound image. An image depth isdetermined which is associated with the identified point or region andthe imaging process is controlled to tailor the imaging to theidentified point or region.

FIG. 1 shows an ultrasound imaging system together with some displayoutputs to show how the user controls the imaging settings.

The system comprises an ultrasound imaging unit 100, i.e. probe, forgenerating ultrasound signals and receiving reflected echo signals. Theimaging unit 100 includes a processing system 102 for controlling thegeneration of the ultrasound signals and processing of the receivedreflected echo signals.

A display 104 is provided for displaying the received ultrasound imagesand a user interface 106 is provided for receiving user commands forcontrolling the generation of the ultrasound signals and/or processingof the received reflected echo signals.

The user interface 106 may comprise a touch screen of the display 104and hence it may be part of the display rather than a separate unit asschematically shown in FIG. 1 . The user interface 106 allows the userto input commands in response to the displayed image. The user interface106 may additionally or alternatively comprise a mouse which is used tocontrol a pointer on the display such that the pointer may be moved to adesired part of the displayed image. There may of course be other userinput controls such as a keyboard, voice recognition etc.

The user interface 106 receives a user input which identifies a point orregion of a displayed ultrasound image.

Pane 108 shows an ultrasound image. Pane 110 shows a user selecting apoint in the image by touching the touch screen display. A single pointmay be identified by touching the screen or a region may be identifiedby drawing a closed shape. Pane 112 shows that a distance d from theimaging unit (ultrasound probe) 100 to the identified point of the imageis derived. This distance d is then used to provide automated orsemi-automated control the generation of the ultrasound signals and/orprocessing of the received reflected echo signals to adapt them to theidentified point or region. The control involves selecting suitableparameters relating to the diagnostic imaging procedure. Examples ofparameters that may be controlled are the focal zone, the frequency, theaperture (i.e. the active size of matrix array), the angular extent ofthe field of view, the imaging depth, the number of scan lines to beacquired within the field of view, settings for gain and dynamic range(e.g. overall gain, time gain compensation, dynamic range during RFconversion and image display), scanning power, scan angle (transducerrotation, e.g. for transesophageal ultrasound probes), use of harmonicfrequencies, smoothing/time averaging, frame rate etc.

In a simplest implementation, the user identifies the point or region,and a standard parameter optimization is carried out.

A feedback unit 114 relates the location of the interaction with theimage to the acquisition geometry. The feedback unit 114 knows theposition of the transducer in the image (and for a 3D dataset also thedisplayed cut-plane), so that the tissue depth of the identified pointor region can be calculated. Using a rule-of-thumb for attenuation suchas 1 dB/cmMHz, the frequency can then be adjusted to ensure at least aminimum amplitude for the returning signal.

The processing system 102 can then relate the user input command to theacquisition parameters and alter the acquisition parameters of theimaging system. Furthermore, the feedback unit 114 and imaging unit 100can be connected in a closed-loop to check that the parameter changeshave the desired effect.

The system thus provides setting adjustments by allowing the user tointeract directly with the image. For example, after taking a firstimage, the user may click into the image at a certain depth (which maybe the maximum depth he/she wants to image with a certain resolution),and the system may then automatically select the best matching frequencyand focus setting for this depth.

The user input may have multiple options, such as a single-click, adouble-click, a one-finger touch interaction or a two-finger touchinteraction, wherein each type of interaction has a different meaning(such as adjusting frequency for a certain point or a focal zone for acertain point).

Specific multi-finger gestures may also be recognized, such as atwo-finger zoom (“pinch gesture”) to adjust the image depth or the fieldof view angle.

For a given type of interaction, menu options may also be presented. Forexample a menu may be used to assign the interaction with a certainmeaning, such as selecting a parameter from a list (e.g. “frequency”,“focal zone” etc. . . . ).

Thus, it can be seen that the user interface in this way can allowfurther commands to be received in addition to the locationidentification.

Some specific examples will now be presented of how multiple commands(location and other commands) may be used.

Time-gain-compensation (TGC) can be adjusted by clicking and sliding ata certain distance from the transducer. As the distance from thetransducer is known, it can be calculated from the depth which TGCsetting needs to be changed. The sliding motion determines how much theTGC for the specified depth should be increased/decreased.

The user may also be allowed to explicitly specify that at givenlocations, a specified amount of signal would be expected (e.g. in theventricle wall or in the mitral valve region). For example, the usercould assign an anatomical region to the point from a drop-down-menu,such as “LV Myocardium”. The system could then adjust the frequency tomaximize the signal, for example, using closed-loop adjustment betweenthe imaging unit 100 and the feedback unit 114, i.e. adjusting thefrequency until the signal is satisfactory.

A further command in addition to location may be used to indicate thatfocal depth adjustment is desired, and the processing system thenadjusts the frequency and/or scanning aperture in response to thederived depth.

A further command may indicate that focal zone adjustment is desired,and the processing system then adjusts the width of the beam at thefocus and the focus depth in response to the derived depth. The beamwidth is for example controlled based on the frequency and aperture, andit determines the resolution at the focus and also at other regionsoutside the focus. The focus depth is the distance from the transducerto the focus point at which the beam width is minimal.

A further command may indicate that a field of view adjustment isdesired, and the processing system is adapted to adjust the field ofview in response to the derived depth. By adjusting the field of view toa region of interest, a zoom in operation is implemented.

As outlined above, many other imaging parameters may be adjusted. Theremay be some parameters which are adjusted automatically in response toan identified anatomical feature or depth, and other parameters whichare adjusted based on user instructions.

FIG. 2 shows a modification to the system of FIG. 1 to identifyanatomical structures within the displayed image and to identify ananatomical structure at the identified point or region. The system maythen apply the best imaging parameters for a particular anatomicalstructure.

For certain adjustments, it may not only be helpful to interact with thedisplayed image, but also to consider the anatomical context. Forexample, contrast enhancement of the boundary between LV myocardium andblood pool is difficult if the location of the boundary in the images isnot known. Also, for automatic frame rate adjustment based on motion ofthe imaged anatomical structure, it may be important if a certain motionis relevant for the acquisition or not.

The same references are used as in FIG. 1 for the same components.

The system has an additional segmentation unit 200. Model-basedsegmentation, neural networks or deep learning may be used foranatomical segmentation. Pane 202 shows an image showing segmentations.Pane 204 shows the user selection of a point or region. The system thendetermines the anatomical structure which has been selected, andprovides image parameter modification to generate an improved imageshown as pane 206.

Different anatomical structures for example make different frame rate,contrast or focal zone appropriate. Selection of the optimal imagingparameters can be performed using a database or directly fromimage/anatomy properties.

The display 104 shows the anatomical context, for example as meshoverlay over the image. The anatomical context is provided by theadapted model of the model-based segmentation. For example, if the modelconsists of a triangular mesh, each triangle may have assignedanatomical labels. This way, the user does not have to assign ananatomical label him or herself.

By way of example, if the user selects a heart valve which is known tomove fast, a higher frame rate is chosen. If the user in the same fieldof view selects the heart chamber, a lower frame rate but higher spatialresolution is selected. This can be done based on stored knowledge abouttypical frame rates required, or based on motion detection.

In another example, the user can select the ventricular wall, and thesystem can optimize the contrast between the wall and surroundingregions. To this end, several frequency, focus and time-gain controlsettings can be tested. For each setting, an objective function iscalculated, such as the difference between the mean intensity inside thewall region and inside the blood region. The setting that maximizes (orfor different objective functions minimizes) the function is used. Analternative objective function would be the more local intensitydifference across a triangular surface, for example, the surfaceseparating the wall and blood region. For image depths at which this islower, the time-gain-compensation setting could be adjusted.

As another example, a structure may be selected in a first acquisition,and for following acquisitions from different probe locations, thesettings are automatically adjusted to best image that structure. Forexample, for a mid-esophageal image of a ventricular septal defect, thedefect is quite far away from the transducer/probe. If the defect isselected in the first acquisition and the probe is moved further downthe esophagus for the acquisition, a higher frequency is automaticallychosen the closer the probe is located to the defect. This alwaysprovides an optimized relation between spatial resolution and signalstrength at the region of interest.

If a structure is selected which is currently only partly in the image,the field of view extent (lateral and depth) may be adjusted such thatthe complete structure is inside the image, or if that is not possible,the largest possible part is visible. This is feasible because from theadapted model, the rough extent of the structure can be estimated.

Thus, it can be seen that there are different possible levels ofautomated or semi-automated control, but they all rely at least onknowledge of the region of an image which has been selected and thecorresponding depth of that anatomical area from the transducer (whetheror not the anatomical area is identified).

FIG. 3 shows an ultrasound imaging method, comprising, in step 300,generating ultrasound signals and receiving and processing reflectedecho signals.

In step 302, a received ultrasound image is displayed and in step 304,user commands for controlling the generation of the ultrasound signalsand/or processing of the received reflected echo signals are received.These user commands identify a point or region of a displayed ultrasoundimage.

The user input identifies a point or region as a touch screen pointidentification, a region drawn over a touch screen, a single click pointidentification using a mouse or a region drawn using a mouse.

The method comprises step 306 of deriving an anatomical featureidentification and/or an image depth associated with the identifiedpoint or region. In step 308, the generation of the ultrasound signalsand/or processing of the received reflected echo signals are controlledto adapt them to the identified point or region.

This may take account of additional user input, such as a touch screenpinch command, a single click mouse or touch screen command, a doubleclick mouse or touch screen command, a two finger touch screeninteraction, a mouse or touch screen slider interaction or a selectionfrom a list of options.

The general operation of the ultrasound system including its driveelectronics can be standard and is not described in detail. However, forcompleteness. FIG. 4 shows an ultrasonic diagnostic imaging system withan array transducer probe according to an example in block diagram form.

In FIG. 4 an ultrasound system 400 is shown which comprises capacitivemicromachined ultrasound transducer (CMUT) cells for transmittingultrasonic waves and receiving echo information. The transducer array410 of the system 400 may be a one- or a two-dimensional array oftransducer elements capable of scanning in a 2D plane or in threedimensions for 3D imaging.

The transducer array 410 is coupled to a micro-beamformer 412 whichcontrols transmission and reception of signals by the CMUT array cells.Micro-beamformers are capable of at least partial beam forming of thesignals received by groups or “patches” of transducer elements forinstance as described in U.S. Pat. No. 5,997,479 (Savord et al.), U.S.Pat. No. 6,013,032 (Savord), and U.S. Pat. No. 6,623,432 (Powers et al.)

The micro-beamformer 412 is coupled by the probe cable, e.g. coaxialwire, to a transmit/receive (T/R) switch 416 which switches betweentransmission and reception modes and protects the main beam former 420from high energy transmit signals when a micro-beamformer is not presentor used and the transducer array 410 is operated directly by the mainbeam former 420. The transmission of ultrasonic beams from thetransducer array 410 under control of the micro-beamformer 412 isdirected by a transducer controller 418 coupled to the micro-beamformerby the T/R switch 416 and the main beam former 420, which receives inputfrom the user's operation of the user control panel or user interface438. One of the functions controlled by the transducer controller 418 isthe direction in which beams are steered and focused. Beams may besteered straight ahead from (orthogonal to) the transducer array 410, orat different angles for a wider field of view. The transducer controller418 may be coupled to control the aforementioned voltage source 101 forthe transducer array 410. For instance, the voltage source 101 sets theDC and AC bias voltage(s) that are applied to the CMUT cells of atransducer array 410, e.g. to generate the ultrasonic RF pulses intransmission mode as explained above.

The partially beam-formed signals produced by the micro-beamformer 412are forwarded to the main beam former 420 where partially beam-formedsignals from individual patches of transducer elements are combined intoa fully beam-formed signal. For example, the main beam former 420 mayhave 128 channels, each of which receives a partially beam-formed signalfrom a patch of dozens or hundreds of CMUT transducer cells. In this waythe signals received by thousands of transducer elements of a transducerarray 410 can contribute efficiently to a single beam-formed signal.

The beam-formed signals are coupled to a signal processor 422. Thesignal processor 422 can process the received echo signals in variousways, such as bandpass filtering, decimation, I and Q componentseparation, and harmonic signal separation which acts to separate linearand nonlinear signals so as to enable the identification of nonlinear(higher harmonics of the fundamental frequency) echo signals returnedfrom tissue and microbubbles.

The signal processor 422 optionally may perform additional signalenhancement such as speckle reduction, signal compounding, and noiseelimination. The bandpass filter in the signal processor 422 may be atracking filter, with its passband sliding from a higher frequency bandto a lower frequency band as echo signals are received from increasingdepths, thereby rejecting the noise at higher frequencies from greaterdepths where these frequencies are devoid of anatomical information.

The processed signals are coupled to a B-mode processor 426 andoptionally to a Doppler processor 428. The B-mode processor 426 employsdetection of an amplitude of the received ultrasound signal for theimaging of structures in the body such as the tissue of organs andvessels in the body. B-mode images of structure of the body may beformed in either the harmonic image mode or the fundamental image modeor a combination of both for instance as described in U.S. Pat. No.6,283,919 (Roundhill et al.) and U.S. Pat. No. 6,458,083 (Jago et al.)

The Doppler processor 428, if present, processes temporally distinctsignals from tissue movement and blood flow for the detection of themotion of substances, such as the flow of blood cells in the imagefield. The Doppler processor typically includes a wall filter withparameters which may be set to pass and/or reject echoes returned fromselected types of materials in the body. For instance, the wall filtercan be set to have a passband characteristic which passes signal ofrelatively low amplitude from higher velocity materials while rejectingrelatively strong signals from lower or zero velocity material.

This passband characteristic will pass signals from flowing blood whilerejecting signals from nearby stationary or slowing moving objects suchas the wall of the heart. An inverse characteristic would pass signalsfrom moving tissue of the heart while rejecting blood flow signals forwhat is referred to as tissue Doppler imaging, detecting and depictingthe motion of tissue. The Doppler processor receives and processes asequence of temporally discrete echo signals from different points in animage field, the sequence of echoes from a particular point referred toas an ensemble. An ensemble of echoes received in rapid succession overa relatively short interval can be used to estimate the Doppler shiftfrequency of flowing blood, with the correspondence of the Dopplerfrequency to velocity indicating the blood flow velocity. An ensemble ofechoes received over a longer period of time is used to estimate thevelocity of slower flowing blood or slowly moving tissue.

The structural and motion signals produced by the B-mode (and Doppler)processor(s) are coupled to a scan converter 432 and a multiplanarreformatter 444. The scan converter 432 arranges the echo signals in thespatial relationship from which they were received in a desired imageformat. For instance, the scan converter may arrange the echo signalinto a two dimensional (2D) sector-shaped format, or a pyramidal threedimensional (3D) image.

The scan converter can overlay a B-mode structural image with colorscorresponding to motion at points in the image field with theirDoppler-estimated velocities to produce a color Doppler image whichdepicts the motion of tissue and blood flow in the image field. Themultiplanar reformatter 444 will convert echoes which are received frompoints in a common plane in a volumetric region of the body into anultrasonic image of that plane, for instance as described in U.S. Pat.No. 6,443,896 (Detmer). A volume renderer 442 converts the echo signalsof a 3D data set into a projected 3D image as viewed from a givenreference point as described in U.S. Pat. No. 6,530,885 (Entrekin etal.)

The 2D or 3D images are coupled from the scan converter 432, multiplanarreformatter 444, and volume renderer 442 to an image processor 430 forfurther enhancement, buffering and temporary storage for display on animage display 440. In addition to being used for imaging, the blood flowvalues produced by the Doppler processor 428 and tissue structureinformation produced by the B-mode processor 426 are coupled to aquantification processor 434. The quantification processor 434 producesmeasures of different flow conditions such as the volume rate of bloodflow as well as structural measurements such as the sizes of organs andgestational age. The quantification processor 434 may receive input fromthe user interface 438, such as the point in the anatomy of an imagewhere a measurement is to be made.

Output data from the quantification processor 434 is coupled to agraphics processor 436 for the reproduction of measurement graphics andvalues with the image on the display 440. The graphics processor 436 canalso generate graphic overlays for display with the ultrasound images.These graphic overlays can contain standard identifying information suchas patient name, date and time of the image, imaging parameters, and thelike. For these purposes the graphics processor 436 receives input fromthe user interface 438, such as patient name.

The user interface 438 is also coupled to the transducer controller 418to control the generation of ultrasound signals from the transducerarray 410 and hence the images produced by the transducer array 410 andthe ultrasound system. The user interface 438 is also coupled to themultiplanar reformatter 444 for selection and control of the planes ofmultiple multiplanar reformatted (MPR) images which may be used toperform quantified measures in the image field of the MPR images.

As will be understood by the skilled person, the above embodiment of anultrasonic diagnostic imaging system is intended to give a non-limitingexample of such an ultrasonic diagnostic imaging system. The skilledperson will immediately realize that several variations in thearchitecture of the ultrasonic diagnostic imaging system are feasiblewithout departing from the teachings of the present invention. Forinstance, as also indicated in the above embodiment, themicro-beamformer 412 and/or the Doppler processor 428 may be omitted,the transducer array 410 may not have 3D imaging capabilities and so on.Other variations will be apparent to the skilled person.

The invention is of interest for general imaging applications or indeedfor guided vascular access such as guidewire, catheter or needle tiptracking.

It should be noted that the above-mentioned embodiments illustraterather than limit the invention, and that those skilled in the art willbe able to design many alternative embodiments without departing fromthe scope of the appended claims. In the claims, any reference signsplaced between parentheses shall not be construed as limiting the claim.The word “comprising” does not exclude the presence of elements or stepsother than those listed in a claim. The word “a” or “an” preceding anelement does not exclude the presence of a plurality of such elements.The invention can be implemented by means of hardware comprising severaldistinct elements. In the device claim enumerating several means,several of these means can be embodied by one and the same item ofhardware. The mere fact that certain measures are recited in mutuallydifferent dependent claims does not indicate that a combination of thesemeasures cannot be used to advantage.

The invention claimed is:
 1. An ultrasound imaging system, comprising:an ultrasound probe for generating ultrasound signals and receivingreflected echo signals; a processing system for controlling thegeneration of the ultrasound signals and processing of the receivedreflected echo signals; a display for displaying a received ultrasoundimage based on the received reflected echo signals; and a user interfacefor receiving user commands from a user for controlling the generationof the ultrasound signals and the processing of the received reflectedecho signals, wherein the user interface is configured to receive a userinput from the user interacting with an ultrasound image displayed onthe display, wherein the user input identifies a point or region ofinterest in the displayed ultrasound image, and wherein the processingsystem is configured to receive input data from the user interfaceindicating the identified point or region of interest in the displayedultrasound image, and automatically, in response to the input data:derive a depth of the identified point or region of interest relative tothe ultrasound probe, identify an anatomical feature associated with theidentified point or region of interest at the derived depth, and adaptthe generation of the ultrasound signals and the processing of thereceived reflected echo signals to the identified point or region ofinterest based on the derived depth and the identified anatomicalfeature at the derived depth.
 2. The system as claimed in claim 1,wherein the processing system is further configured to adjust at leastone of: a frame rate; a contrast; a gain setting; or a focal zone. 3.The system as claimed in claim 1, wherein the processing system isconfigured to adapt the generation of the ultrasound signals byadjusting frequency of the ultrasound signals in response to the deriveddepth.
 4. The system as claimed in claim 1, wherein the processingsystem is configured to adapt the generation of the ultrasound signalsby adjusting frequency of the ultrasound signals to maximize thereceived reflected echo signals.
 5. The system as claimed in claim 1,wherein the processing system is configured to further identifyanatomical structures within the displayed ultrasound image, and tofurther adapt the generation of the ultrasound signals and theprocessing of the received reflected echo signals to the identifiedanatomical structures.
 6. The system as claimed in claim 1, wherein theuser interface is further configured to receive a further user commandindicating that focal depth adjustment is desired, and the processingsystem is further configured to adjust frequency of the ultrasoundsignals in response to the derived depth.
 7. The system as claimed inclaim 1, wherein the user interface is further configured to receivefurther user command as at least one of: a touch screen pinch command; asingle click mouse or touch screen command; a double click mouse ortouch screen command; a two finger touch screen interaction; a mouse ortouch screen slider interaction; or a selection from a list of options.8. The system as claimed in claim 1, wherein the user interface isfurther configured to receive the user input as at least one of: a touchscreen point identification; a region drawn over a touch screen; asingle click point identification using a mouse; or a region drawn usinga mouse.
 9. An ultrasound imaging method, comprising: generatingultrasound signals and receiving and processing reflected echo signals;displaying a received ultrasound image based on the received reflectedecho signals; receiving a user input via a user interface from a userinteracting with the ultrasound image displayed on the display toidentify a point or region of interest in the displayed ultrasoundimage; receiving input data from the user interface indicating theidentified point or region of interest in the displayed ultrasoundimage; and automatically, in response to the input data: deriving adepth of the identified point or region of interest; identifying ananatomical feature associated with the identified point or region ofinterest at the derived depth; and adapting the generation of theultrasound signals and processing of the received reflected echo signalsto the identified point or region of interest based on the derived depthand the identified anatomical feature at the derived depth.
 10. Themethod as claimed in claim 9, wherein adapting the generation of theultrasound signals comprises adjusting at least one of: a frame rate; acontrast; a gain setting; or a focal zone.
 11. The method as claimed inclaim 9, wherein adapting the generation of the ultrasound signalscomprises adapting frequency of the ultrasound signals in response tothe derived depth.
 12. The method as claimed in claim 9, furthercomprising: identifying anatomical structures within the displayedultrasound image; and further adapting the generation of the ultrasoundsignals and processing of the received reflected echo signals to theidentified anatomical structures.
 13. The method as claimed in claim 9,further comprising receiving a further user command indicating thatfocal depth adjustment is desired, and adjusting frequency of theultrasound signals in response to the derived depth.
 14. The method asclaimed in claim 13, wherein receiving the user input comprises as atleast one of: a touch screen pinch command; a single click mouse ortouch screen command; a double click mouse or touch screen command; atwo finger touch screen interaction; a mouse or touch screen sliderinteraction; or a selection from a list of options.
 15. The system asclaimed in claim 1, wherein the user interface is further configured toreceive a further user command indicating that focal zone adjustment isdesired, and the processing system is further configured to adjust awidth of a beam of the ultrasound signals at a focus and a focus depthin response to the derived depth.
 16. The system as claimed in claim 1,wherein the user interface is further configured to receive a furtheruser command indicating that adjustment of a field of view is desired,and the processing system is further configured to adjust the field ofview in response to the derived depth.
 17. The system as claimed inclaim 1, wherein the user interface is further configured to receive afurther user command indicating that adjustment of time gaincompensation is desired, and the processing system is further configuredto adjust the time gain compensation in response to the derived depth.18. The method as claimed in claim 9, further comprising receiving afurther user command indicating that focal zone adjustment is desired,and adjusting a width of a beam of the ultrasound signals at a focus anda focus depth in response to the derived depth.
 19. The method asclaimed in claim 9, further comprising receiving a further user commandindicating that adjustment of time gain compensation is desired, andadapting the time gain compensation in response to the derived depth.20. The system of claim 1, wherein the user interface comprises atouchscreen on the display, and wherein the user input comprises a touchon the touchscreen identifying the point of interest or a drawing on thetouchscreen identifying the region of interest.